The use of shell and tube heat exchangers for waste heat recovery has shown excellent results in increasing engine performance, as well as offering a large surface area for small volumes, ease of cleaning, good mechanical layout, and well-known design procedure. This article presents the modeling of the coupling circuit and thermo-fluid design of the heat exchangers in the thermal oil circuit in order to maximize the heat transfer of this equipment at the lowest pressure drop and acquisition cost, which is obtained with a smaller heat transfer area. The research results show the existence of optimal values for the studied system parameters, type of organic working fluid, type of heat exchangers, besides the size of the other system components, which are particular for the studied application. However, these results cannot be compared with the real projects already implemented in the industry due to their absence. It has been verified that the fluids that have showed the best performance in terms of thermal efficiency have been acetone and benzene, with an overall thermal efficiency of 17% and 15%, respectively.